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pcl-720 image

Digital I/O and Counter Card


Ordering Information

Introduction Return to top of page

The PCL-720 Digital I/O and Counter Card is a PC compatible add-on card with 32 digital input channels, 32 digital output channels and three programmable counter/timer channels.

Its digital I/O channels are TTL-compatible and use 74LS244 driver/buffer circuits to provide higher driving capacity for outputs. These buffered circuits also require lower loading current for input than the regular TTL circuits.

The PCL-720's Intel 8253 programmable timer/counter provides three flexible 16-bit timer/counter channels. You can generate waves and pulses by programming the 8253. Jumper settings determine clock crystal frequency. The PCL-720 also includes a breadboard area perfect for customized circuits.

Applications Return to top of page

  • Digital input
    Contact-closure monitor
    Switch-panel status sensor BCD interface receiver
    Digital signal interface
  • Digital output
    Industrial ON/OFF controller
    Digital signal interface
    BCD interface driver
  • Counter/timer
    Period and pulse-width measurement
    Event and frequency counting
    Waveform and pulse generation

Features Return to top of page

  • 32 TTL digital input channels 3
  • 2 TTL digital output channels
  • High output driving capacity
  • Low input loading
  • Three programmable counter/timer channels
  • User configurable clock source
  • Breadboard area for custom circuits

Specifications Return to top of page

Digital input

  • Logic level 0: 0.8 V max
  • Logic level 1: 2.0 V min.

Digital output

  • Logic level 0: 0.5 V max. @ 24 mA (sink)
  • Logic level 1: 2.0 V min. @ 15 mA (source)

Programmable counter/timer

  • Frequency range: 0 to 2.6 MHz
  • Counters: Three independent 16-bit counters
  • Modes: Six programmable modes
  • Usable pins: CLOCK and GATE for each channel

Clock Source

  • Clock frequency: 2 MHz, 1 MHz, 500 KHz or 250 KHz; jumper selectable
  • Frequency divider: divided by 1, 10, 100 or user adjustable


  • Transfer rate: 300 Kbps typical, 500 Kbps max.
  • Power consumption: 5 V @ 500 mA typical
  • Dimensions: 8" x 3/4" (205mm x 95 mm)
  • I/O port address: Eight consecutive bytes from hex 200 to hex 3F8
  • Breadboard area: 651 (31 x 21) plated-through "donuts", each with a .036" hole on .10" centers

Ordering Information Return to top of page


Digital I/O and Counter Card, user's manual

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USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1364
Point Roberts, WA 98281

Western Canada - Vancouver BC

Tel:1.800.663.6001 or 1.604.925.6150
Address: 2454 Haywood Ave
West Vancouver, BC V7V 1Y1

Eastern Canada - Markham, Ontario

Tel:1.800.465.0164 or 1.905.513.7027